Short message services are very popular today. Besides text-based short messages, means are also required for transmitting multimedia data. A multimedia messaging service (MMS) is a service which has been developed for transferring messages with various content types, such as video, audio and images. The 3GPP (3rd Generation Partnership Project) specification TS 23.140 v. 6.7.0 “Multimedia Messaging Service (MMS); Functional Description; Stage 2”, September 2004, describes the basic functions of the MMS.
A multimedia messaging service may be arranged in an environment comprising different network types. The 3GPP MMS environment may comprise 2 G and 3 G networks and provides all the necessary service elements for multimedia messaging, such as delivery, storage and notification functionality. An MMS relay/server is responsible for storage and handling of incoming and outgoing messages and for the transfer of messages between different messaging systems. An MMS user agent resides on a mobile terminal transmitting or receiving multimedia messages. The MMS user agent is an application layer function that provides users with the ability to view, compose and handle multimedia messages (MM).
Multiple content types may be transmitted by MMS. An MM describes the content type of the message, for instance “jpeg” in the case of an image in the jpeg format being transmitted. An originator user agent adds an identifier of a MIME (multi-purpose Internet mail extensions) content type of an MM to the MM PDU (packet data unit). The identifier of the MIME content type is transferred by an intermediate MMS relay/server to a recipient user agent.
The 3GPP MMS also supports content adaptation. A number of content classes is specified in an OMA (Open Mobile Alliance) specification “MMS Conformance Document 1.2”, Candidate Version 27 Jul. 2004. The content classes illustrated in Table 1 define content categorizations. Each content class defines particular requirements which a user agent must support in order to support the content class. An identifier of one of the content classes may be included in an MM from an originator user agent if the content of the MM is in conformance with requirements of the content class. This content class identifier, as well as other content information, such as an indication of presence of DRM (Digital Rights Management) protection, may be provided by an originator MMS user agent to the MMS relay/server. The MMS relay/server may use this content class information for identifying whether an adaptation is necessary: On the basis of the recipient MMS user agent properties and the received content class the (recipient) MMS relay/server may define if an adaptation is required.
If a recipient terminal wishes to obtain details of the content of a received MM (besides the content type), it needs to perform analysis of the content, i.e. analyse the body part of the MM. This may be very complex process and requires time and processing resources.